The invention relates to various image processing apparatuses such as image diagnosing apparatus for a medical use, video processing apparatus for a broadcasting use, image processing apparatus for an industrial use, image photographing display apparatus for a commercial use, and the like, in which an information carrier such as electromagnetic wave including a light, X-rays, or the like, ultrasonic wave, or the like is irradiated or inputted to an object and a change in information carrier is measured, thereby obtaining image information. More particularly, the invention relates to an image processing apparatus in which peculiar noise or character which an apparatus system has with respect to the image information obtained as mentioned above is eliminated, the noise are reduced without being accompanied with a blur due to a motion, or an image is converted into an image that is preferably matched with a taste of the user, so that an accurate image with a large transfer information amount can be provided.
In a conventional image processing apparatus, in case of eliminating peculiar noise or character which the apparatus system has, the noise or character that is peculiar to the system is first modeled, and the noise or character is eliminated on the basis of the model. For example, when explaining with respect to the case of an X-ray photographing apparatus, there are noise and a spatial blur as factors which cause a deterioration in picture quality of an X-ray image that is obtained by the X-ray photographing apparatus. As noise which are mixed into the X-ray image, there are X-ray quantum noise based on the generation and annihilation stage of an X-ray photon. Those noise can be modeled by white Gaussian random noise. The X-ray photographing apparatus is handled as a linear system, a blur function is obtained from its impulse response, and the blur is approximated by a Gaussian function or the like, thereby modeling.
The prior arts regarding the present invention are shown below.
(1) An example in which a neural network is used to eliminate Gaussian random noise mixed into a 2-dimensional image has been reported. [Kaoru Arakawa and Hiroshi Harashima, "Designing of Layered-Neural Non-linear Filters using Back Propagation Algorithm", the papers of The Institute of Electronics Information and Communication Engineers of Japan, Vol. J74-A, No. 3, pages 421-429, 1991]. According to the above paper, an .epsilon. filter is realized by a neural network.
(2) An example in which a binarization of a 2-dimensional image is realized by a neural network has been reported. [U.S. Pat. No. 5,091,965 (1992)]
(3) An example in which a rank filter is realized by a neural network has been reported. [U.S. Pat. No. 5,113,484 (1992)]
(4) An example in which a neural network is used as a defect corrector of a video signal has been reported. [U.S. Pat. No. 5,161,014 (1992)] According to the above paper, a defect correction filter is realized by a neural network.
In case of eliminating the peculiar noise or character which the system has and extracting meaning information, in an actual image processing system, a possibility such that the peculiar noise or character which the system has a mere spatial extent is very small, and in many cases, such noise or character has a time-dependent and spatial extent. It is extremely difficult to distinguish such peculiar noise or character from the meaning information from only information merely having a spatial extent. It is necessary to integrally judge from information having a time-dependent and spatial extent. In case of the above conventional apparatus, however, since they are judged from only the information having a spatial extent, the noise or character is not sufficiently eliminated. In case of reducing the noise without being accompanied with a blur due to a motion as well, even in case of distinguishing an object which time-spatially moves from the noise, they are judged from only the information having a spatial extent, so that the noise or character cannot be sufficiently eliminated.
In case of providing an image which is preferably matched with a taste of the user, since the above conventional apparatus doesn't have a function such that an image or information that is provided by the user or the like is given at the present location, an image which is preferably matched with a taste of the user cannot be provided.